Impact of reward on pain threshold and tolerance to experimental pain (Cold Pressor Task) in healthy subjects and patients with schizophrenia.

Reduced pain sensitivity is considered as a potential endophenotype of schizophrenia. Patient's motivation in pain experimental studies was neither assessed nor controlled. This study aimed to assess the effect of reward on pain in patients with schizophrenia compared to controls. Rewarded subjects showed higher pain threshold and tolerance compared to unrewarded subjects. Pain tolerance was significantly lower in patients than in controls when they were not rewarded. Reward resulted in an increase of pain tolerance with a higher manner in patients. This study suggests that better control of motivational aspects could improve assessment of pain sensitivity in schizophrenia.